Sexually experienced adolescents less than 19 years of age are at greater risk for the acquisition of sexually transmitted diseases (STDs) and typically have higher STD rates than other age- specific groups. Nationally, this population accounted for about a quarter of all reportable STDs. In Mississippi (MS), this age group also accounted for greater than 40 percent of the common reportable STDs in 1998. Despite such alarming STD rates, African American adolescents are at even greater risk for contracting STDs, including the human immunodeficiency virus (HIV) infection, and unplanned pregnancies. Few studies have documented the relative benefits of safer-sex and theory-based abstinence risk reduction programs as the framework for achieving effective change in risky behaviors among vulnerable adolescents. However, these models have been marred by either (1) the lack of sustainability, generalizability and replicability of the intervention effects, and/or (2) the integration of contraceptive knowledge and sexual negotiation skills into theory-based abstinence programs, strategies not in conformity with the conceptual framework of "pure" abstinence. Additionally, the National Institutes of Health (NIH) Consensus Panel recently highlighted the lack of sufficient scientific knowledge concerning the relative effectiveness of broader-based safer sex intervention versus the narrowly focused abstinence intervention funded by the United States (US) Congress under the current Welfare Reform Act. While the debate lingers among behavioral scientists and policy makers, studies designed to provide critical information and scientific knowledge for reaching a consensus concerning the relative efficacy of safer sex and "pure" abstinence-based interventions are scanty. Nevertheless, the fundamental research questions remain unanswered: Which behavioral interventions are the most appropriate, realistic and effective? Which mechanisms do exist to sustain and augment intervention effects on adolescent HIV- risk behaviors? What is the role of biological markers in behavioral research? Hence, the primary focus of this proposed study. Therefore, over a five-year period, we propose (A) to recruit 450 African American at-risk youths ages 12-16 years from inner-city youth serving organizations (YSOs) and a comprehensive community- based health center in Jackson, MS; (B) to stratify, and randomize into 1 of 2 culturally-sensitive and age-appropriate theory-based STD/HIV risk reduction interventions and an experimental control condition-- (1) safer sex group: Becoming A Responsible Team (BART) Program; (2) Abstinence group: Advisor/Advisee Character Education Program; and (3) the experimental control group: African History (AKOMA)-- consisting of 8 modules of 1-hourly interactive instructional lessons per week, coordinated by trained community health facilitators; and (C) to finally evaluate the role and value of biological markers in behavioral research by longitudinally assessing the enrolled participants at baseline, and 6-, 12- and 18-months post- intervention for behavioral outcome measures, as well as, life skills that are critical in eliciting answers to our research questions.